Pileus Git - grits/blob - src/roam.c

   1 /*
   2  * Copyright (C) 2009-2010 Andy Spencer <andy753421@gmail.com>
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /**
  19  * SECTION:roam
  20  * @short_description: Realtime Optimally-Adapting Meshes
  21  *
  22  * A spherical version of the Realtime Optimally-Adapting Meshes (ROAM)
  23  * algorithm is use for drawing the surface of the planet. ROAM provide a
  24  * continuous level-of-detail mesh of the planet which is used by #GisOpenGL
  25  * when drawing surface textures for GisTiles.
  26  *
  27  * This implementation of the ROAM algorithm is based on an octahedron as the
  28  * base model.
  29  */
  30
  31 #include <glib.h>
  32 #include <math.h>
  33 #include <string.h>
  34 #include <GL/gl.h>
  35 #include <GL/glu.h>
  36
  37 #include "gpqueue.h"
  38 #include "gis-util.h"
  39 #include "roam.h"
  40
  41 /*
  42  * TODO:
  43  *   - Optimize for memory consumption
  44  *   - Profile for computation speed
  45  *   - Target polygon count/detail
  46  */
  47
  48 /* For GPQueue comparators */
  49 static gint tri_cmp(RoamTriangle *a, RoamTriangle *b, gpointer data)
  50 {
  51         if      (a->error < b->error) return  1;
  52         else if (a->error > b->error) return -1;
  53         else                          return  0;
  54 }
  55 static gint dia_cmp(RoamDiamond *a, RoamDiamond *b, gpointer data)
  56 {
  57         if      (a->error < b->error) return -1;
  58         else if (a->error > b->error) return  1;
  59         else                          return  0;
  60 }
  61
  62
  63 /*************
  64  * RoamPoint *
  65  *************/
  66 /**
  67  * roam_point_new:
  68  * @lat:  the latitude for the point
  69  * @lon:  the longitude for the point
  70  * @elev: the elevation for the point
  71  *
  72  * Create a new point at the given locaiton
  73  *
  74  * Returns: the new point
  75  */
  76 RoamPoint *roam_point_new(gdouble lat, gdouble lon, gdouble elev)
  77 {
  78         RoamPoint *point = g_new0(RoamPoint, 1);
  79         point->lat  = lat;
  80         point->lon  = lon;
  81         point->elev = elev;
  82         /* For get_intersect */
  83         lle2xyz(lat, lon, elev, &point->x, &point->y, &point->z);
  84         return point;
  85 }
  86
  87 /**
  88  * roam_point_add_triangle:
  89  * @point:    the point
  90  * @triangle: the to add
  91  *
  92  * Associating a triangle with a point and update it's vertex normal.
  93  */
  94 void roam_point_add_triangle(RoamPoint *point, RoamTriangle *triangle)
  95 {
  96         for (int i = 0; i < 3; i++) {
  97                 point->norm[i] *= point->tris;
  98                 point->norm[i] += triangle->norm[i];
  99         }
 100         point->tris++;
 101         for (int i = 0; i < 3; i++)
 102                 point->norm[i] /= point->tris;
 103 }
 104
 105 /**
 106  * roam_point_remove_triangle:
 107  * @point:    the point
 108  * @triangle: the to add
 109  *
 110  * Un-associating a triangle with a point and update it's vertex normal.
 111  */
 112 void roam_point_remove_triangle(RoamPoint *point, RoamTriangle *triangle)
 113 {
 114         for (int i = 0; i < 3; i++) {
 115                 point->norm[i] *= point->tris;
 116                 point->norm[i] -= triangle->norm[i];
 117         }
 118         point->tris--;
 119         if (point->tris)
 120                 for (int i = 0; i < 3; i++)
 121                         point->norm[i] /= point->tris;
 122 }
 123
 124 /**
 125  * roam_point_update_height:
 126  * @point: the point
 127  *
 128  * Update the height (elevation) of a point based on the current height function
 129  */
 130 void roam_point_update_height(RoamPoint *point)
 131 {
 132         if (point->height_func) {
 133                 gdouble elev = point->height_func(
 134                                 point->lat, point->lon, point->height_data);
 135                 lle2xyz(point->lat, point->lon, elev,
 136                                 &point->x, &point->y, &point->z);
 137         }
 138 }
 139
 140 /**
 141  * roam_point_update_projection:
 142  * @point: the point
 143  * @view:  the view to use when projecting the point
 144  *
 145  * Updated the screen-space projection of a point.
 146  */
 147 void roam_point_update_projection(RoamPoint *point, RoamView *view)
 148 {
 149         static int count   = 0;
 150         static int version = 0;
 151         if (version != view->version) {
 152                 g_debug("RoamPoint: Projected %d points", count);
 153                 count   = 0;
 154                 version = view->version;
 155         }
 156
 157         if (point->pversion != view->version) {
 158                 /* Cache projection */
 159                 gluProject(point->x, point->y, point->z,
 160                         view->model, view->proj, view->view,
 161                         &point->px, &point->py, &point->pz);
 162                 point->pversion = view->version;
 163                 count++;
 164         }
 165 }
 166
 167 /****************
 168  * RoamTriangle *
 169  ****************/
 170 /**
 171  * roam_triangle_new:
 172  * @l: the left point
 173  * @m: the middle point
 174  * @r: the right point
 175  *
 176  * Create a new triangle consisting of three points.
 177  *
 178  * Returns: the new triangle
 179  */
 180 RoamTriangle *roam_triangle_new(RoamPoint *l, RoamPoint *m, RoamPoint *r,
 181                 RoamDiamond *parent)
 182 {
 183         RoamTriangle *triangle = g_new0(RoamTriangle, 1);
 184
 185         triangle->error  = 0;
 186         triangle->p.l    = l;
 187         triangle->p.m    = m;
 188         triangle->p.r    = r;
 189         triangle->parent = parent;
 190         triangle->split  = roam_point_new(
 191                 (l->lat + r->lat)/2,
 192                 (ABS(l->lat) == 90 ? r->lon :
 193                  ABS(r->lat) == 90 ? l->lon :
 194                  lon_avg(l->lon, r->lon)),
 195                 (l->elev + r->elev)/2);
 196         /* TODO: Move this back to sphere, or actually use the nesting */
 197         triangle->split->height_func = m->height_func;
 198         triangle->split->height_data = m->height_data;
 199         roam_point_update_height(triangle->split);
 200         //if ((float)triangle->split->lat > 44 && (float)triangle->split->lat < 46)
 201         //      g_debug("RoamTriangle: new - (l,m,r,split).lats = %7.2f %7.2f %7.2f %7.2f",
 202         //                      l->lat, m->lat, r->lat, triangle->split->lat);
 203         //if ((float)l->lat == (float)r->lat &&
 204         //    (float)triangle->split->lat != (float)l->lat)
 205         //      g_warning("RoamTriangle: new - split.lat=%f != (l=r).lat=%f",
 206         //              triangle->split->lat, l->lat);
 207
 208         /* Update normal */
 209         double pa[3];
 210         double pb[3];
 211         pa[0] = triangle->p.l->x - triangle->p.m->x;
 212         pa[1] = triangle->p.l->y - triangle->p.m->y;
 213         pa[2] = triangle->p.l->z - triangle->p.m->z;
 214
 215         pb[0] = triangle->p.r->x - triangle->p.m->x;
 216         pb[1] = triangle->p.r->y - triangle->p.m->y;
 217         pb[2] = triangle->p.r->z - triangle->p.m->z;
 218
 219         triangle->norm[0] = pa[1] * pb[2] - pa[2] * pb[1];
 220         triangle->norm[1] = pa[2] * pb[0] - pa[0] * pb[2];
 221         triangle->norm[2] = pa[0] * pb[1] - pa[1] * pb[0];
 222
 223         double total = sqrt(triangle->norm[0] * triangle->norm[0] +
 224                             triangle->norm[1] * triangle->norm[1] +
 225                             triangle->norm[2] * triangle->norm[2]);
 226
 227         triangle->norm[0] /= total;
 228         triangle->norm[1] /= total;
 229         triangle->norm[2] /= total;
 230
 231         /* Store bounding box, for get_intersect */
 232         RoamPoint *p[] = {l,m,r};
 233         triangle->edge.n =  -90; triangle->edge.s =  90;
 234         triangle->edge.e = -180; triangle->edge.w = 180;
 235         gboolean maxed = FALSE;
 236         for (int i = 0; i < G_N_ELEMENTS(p); i++) {
 237                 triangle->edge.n = MAX(triangle->edge.n, p[i]->lat);
 238                 triangle->edge.s = MIN(triangle->edge.s, p[i]->lat);
 239                 if (p[i]->lat == 90 || p[i]->lat == -90)
 240                         continue;
 241                 if (p[i]->lon == 180) {
 242                         maxed = TRUE;
 243                         continue;
 244                 }
 245                 triangle->edge.e = MAX(triangle->edge.e, p[i]->lon);
 246                 triangle->edge.w = MIN(triangle->edge.w, p[i]->lon);
 247         }
 248         if (maxed) {
 249                 if (triangle->edge.e < 0)
 250                         triangle->edge.w = -180;
 251                 else
 252                         triangle->edge.e =  180;
 253         }
 254
 255         //g_message("roam_triangle_new: %p", triangle);
 256         return triangle;
 257 }
 258
 259 /**
 260  * roam_triangle_free:
 261  * @triangle: the triangle
 262  *
 263  * Free data associated with a triangle
 264  */
 265 void roam_triangle_free(RoamTriangle *triangle)
 266 {
 267         g_free(triangle->split);
 268         g_free(triangle);
 269 }
 270
 271 /**
 272  * roam_triangle_add:
 273  * @triangle: the triangle
 274  * @left:     the left neighbor
 275  * @base:     the base neighbor
 276  * @right:    the right neighbor
 277  * @sphere:   the sphere to add the triangle to
 278  *
 279  * Add a triangle into the sphere's mesh using the given neighbors.
 280  */
 281 void roam_triangle_add(RoamTriangle *triangle,
 282                 RoamTriangle *left, RoamTriangle *base, RoamTriangle *right,
 283                 RoamSphere *sphere)
 284 {
 285         triangle->t.l = left;
 286         triangle->t.b = base;
 287         triangle->t.r = right;
 288
 289         roam_point_add_triangle(triangle->p.l, triangle);
 290         roam_point_add_triangle(triangle->p.m, triangle);
 291         roam_point_add_triangle(triangle->p.r, triangle);
 292
 293         if (sphere->view)
 294                 roam_triangle_update_errors(triangle, sphere);
 295
 296         triangle->handle = g_pqueue_push(sphere->triangles, triangle);
 297 }
 298
 299 /**
 300  * roam_triangle_remove:
 301  * @triangle: the triangle
 302  * @sphere:   the sphere to remove the triangle from
 303  *
 304  * Remove a triangle from a sphere's mesh.
 305  */
 306 void roam_triangle_remove(RoamTriangle *triangle, RoamSphere *sphere)
 307 {
 308         /* Update vertex normals */
 309         roam_point_remove_triangle(triangle->p.l, triangle);
 310         roam_point_remove_triangle(triangle->p.m, triangle);
 311         roam_point_remove_triangle(triangle->p.r, triangle);
 312
 313         g_pqueue_remove(sphere->triangles, triangle->handle);
 314 }
 315
 316 static void roam_triangle_sync_neighbors(RoamTriangle *new, RoamTriangle *old, RoamTriangle *neigh)
 317 {
 318         if      (neigh->t.l == old) neigh->t.l = new;
 319         else if (neigh->t.b == old) neigh->t.b = new;
 320         else if (neigh->t.r == old) neigh->t.r = new;
 321         else g_assert_not_reached();
 322 }
 323
 324 static gboolean roam_triangle_visible(RoamTriangle *triangle, RoamSphere *sphere)
 325 {
 326         RoamPoint *l = triangle->p.l;
 327         RoamPoint *m = triangle->p.m;
 328         RoamPoint *r = triangle->p.r;
 329         gdouble min_x = MIN(MIN(l->px, m->px), r->px);
 330         gdouble max_x = MAX(MAX(l->px, m->px), r->px);
 331         gdouble min_y = MIN(MIN(l->py, m->py), r->py);
 332         gdouble max_y = MAX(MAX(l->py, m->py), r->py);
 333         gint *view = sphere->view->view;
 334         return !(max_x < view[0] || min_x > view[2] ||
 335                  max_y < view[1] || min_y > view[3]) &&
 336                  l->pz > 0 && m->pz > 0 && r->pz > 0 &&
 337                  l->pz < 1 && m->pz < 1 && r->pz < 1;
 338 }
 339
 340 /**
 341  * roam_triangle_update_errors:
 342  * @triangle: the triangle
 343  * @sphere:   the sphere to use when updating errors
 344  *
 345  * Update the error value associated with a triangle. Called when the view
 346  * changes.
 347  */
 348 void roam_triangle_update_errors(RoamTriangle *triangle, RoamSphere *sphere)
 349 {
 350         /* Update points */
 351         roam_point_update_projection(triangle->p.l, sphere->view);
 352         roam_point_update_projection(triangle->p.m, sphere->view);
 353         roam_point_update_projection(triangle->p.r, sphere->view);
 354
 355         if (!roam_triangle_visible(triangle, sphere)) {
 356                 triangle->error = -1;
 357         } else {
 358                 roam_point_update_projection(triangle->split, sphere->view);
 359                 RoamPoint *l     = triangle->p.l;
 360                 RoamPoint *m     = triangle->p.m;
 361                 RoamPoint *r     = triangle->p.r;
 362                 RoamPoint *split = triangle->split;
 363
 364                 /*               l-r midpoint        projected l-r midpoint */
 365                 gdouble pxdist = (l->px + r->px)/2 - split->px;
 366                 gdouble pydist = (l->py + r->py)/2 - split->py;
 367
 368                 triangle->error = sqrt(pxdist*pxdist + pydist*pydist);
 369
 370                 /* Multiply by size of triangle */
 371                 double size = -( l->px * (m->py - r->py) +
 372                                  m->px * (r->py - l->py) +
 373                                  r->px * (l->py - m->py) ) / 2.0;
 374
 375                 /* Size < 0 == backface */
 376                 triangle->error *= size;
 377         }
 378 }
 379
 380 /**
 381  * roam_triangle_split:
 382  * @triangle: the triangle
 383  * @sphere:   the sphere
 384  *
 385  * Split a triangle into two child triangles and update the sphere.
 386  * triangle
 387  */
 388 void roam_triangle_split(RoamTriangle *triangle, RoamSphere *sphere)
 389 {
 390         //g_message("roam_triangle_split: %p, e=%f\n", triangle, triangle->error);
 391
 392         sphere->polys += 2;
 393
 394         if (triangle != triangle->t.b->t.b)
 395                 roam_triangle_split(triangle->t.b, sphere);
 396         if (triangle != triangle->t.b->t.b)
 397                 g_assert_not_reached();
 398
 399         RoamTriangle *s = triangle;      // Self
 400         RoamTriangle *b = triangle->t.b; // Base
 401
 402         RoamDiamond *dia = roam_diamond_new(s, b);
 403
 404         /* Add new triangles */
 405         RoamPoint *mid = triangle->split;
 406         RoamTriangle *sl = s->kids[0] = roam_triangle_new(s->p.m, mid, s->p.l, dia); // Self Left
 407         RoamTriangle *sr = s->kids[1] = roam_triangle_new(s->p.r, mid, s->p.m, dia); // Self Right
 408         RoamTriangle *bl = b->kids[0] = roam_triangle_new(b->p.m, mid, b->p.l, dia); // Base Left
 409         RoamTriangle *br = b->kids[1] = roam_triangle_new(b->p.r, mid, b->p.m, dia); // Base Right
 410
 411         /*                triangle,l,  base,      r,  sphere */
 412         roam_triangle_add(sl, sr, s->t.l, br, sphere);
 413         roam_triangle_add(sr, bl, s->t.r, sl, sphere);
 414         roam_triangle_add(bl, br, b->t.l, sr, sphere);
 415         roam_triangle_add(br, sl, b->t.r, bl, sphere);
 416
 417         roam_triangle_sync_neighbors(sl, s, s->t.l);
 418         roam_triangle_sync_neighbors(sr, s, s->t.r);
 419         roam_triangle_sync_neighbors(bl, b, b->t.l);
 420         roam_triangle_sync_neighbors(br, b, b->t.r);
 421
 422         /* Remove old triangles */
 423         roam_triangle_remove(s, sphere);
 424         roam_triangle_remove(b, sphere);
 425
 426         /* Add/Remove diamonds */
 427         roam_diamond_update_errors(dia, sphere);
 428         roam_diamond_add(dia, sphere);
 429         roam_diamond_remove(s->parent, sphere);
 430         roam_diamond_remove(b->parent, sphere);
 431 }
 432
 433 /**
 434  * roam_triangle_draw:
 435  * @triangle: the triangle
 436  *
 437  * Draw the triangle. Use for debugging.
 438  */
 439 void roam_triangle_draw(RoamTriangle *triangle)
 440 {
 441         glBegin(GL_TRIANGLES);
 442         glNormal3dv(triangle->p.r->norm); glVertex3dv((double*)triangle->p.r);
 443         glNormal3dv(triangle->p.m->norm); glVertex3dv((double*)triangle->p.m);
 444         glNormal3dv(triangle->p.l->norm); glVertex3dv((double*)triangle->p.l);
 445         glEnd();
 446         return;
 447 }
 448
 449 /**
 450  * roam_triangle_draw_normal:
 451  * @triangle: the triangle
 452  *
 453  * Draw a normal vector for the triangle. Used while debugging.
 454  */
 455 void roam_triangle_draw_normal(RoamTriangle *triangle)
 456 {
 457         double center[] = {
 458                 (triangle->p.l->x + triangle->p.m->x + triangle->p.r->x)/3.0,
 459                 (triangle->p.l->y + triangle->p.m->y + triangle->p.r->y)/3.0,
 460                 (triangle->p.l->z + triangle->p.m->z + triangle->p.r->z)/3.0,
 461         };
 462         double end[] = {
 463                 center[0]+triangle->norm[0]*2000000,
 464                 center[1]+triangle->norm[1]*2000000,
 465                 center[2]+triangle->norm[2]*2000000,
 466         };
 467         glBegin(GL_LINES);
 468         glVertex3dv(center);
 469         glVertex3dv(end);
 470         glEnd();
 471 }
 472
 473 /***************
 474  * RoamDiamond *
 475  ***************/
 476 /**
 477  * roam_diamond_new:
 478  * @parent0: a parent triangle
 479  * @parent1: a parent triangle
 480  * @kid0:    a child triangle
 481  * @kid1:    a child triangle
 482  * @kid2:    a child triangle
 483  * @kid3:    a child triangle
 484  *
 485  * Create a diamond to store information about two split triangles.
 486  *
 487  * Returns: the new diamond
 488  */
 489 RoamDiamond *roam_diamond_new(RoamTriangle *parent0, RoamTriangle *parent1)
 490 {
 491         RoamDiamond *diamond = g_new0(RoamDiamond, 1);
 492         diamond->parents[0] = parent0;
 493         diamond->parents[1] = parent1;
 494         return diamond;
 495 }
 496
 497 /**
 498  * roam_diamond_add:
 499  * @diamond: the diamond
 500  * @sphere:  the sphere to add the diamond to
 501  *
 502  * Add a diamond into the sphere's pool of diamonds. It will be check for
 503  * possible merges.
 504  */
 505 void roam_diamond_add(RoamDiamond *diamond, RoamSphere *sphere)
 506 {
 507         diamond->active = TRUE;
 508         diamond->error  = MAX(diamond->parents[0]->error, diamond->parents[1]->error);
 509         diamond->handle = g_pqueue_push(sphere->diamonds, diamond);
 510 }
 511
 512 /**
 513  * roam_diamond_remove:
 514  * @diamond: the diamond
 515  * @sphere:  the sphere to remove the diamond from
 516  *
 517  * Remove a diamond from the sphere's pool of diamonds.
 518  */
 519 void roam_diamond_remove(RoamDiamond *diamond, RoamSphere *sphere)
 520 {
 521         if (diamond && diamond->active) {
 522                 diamond->active = FALSE;
 523                 g_pqueue_remove(sphere->diamonds, diamond->handle);
 524         }
 525 }
 526
 527 /**
 528  * roam_diamond_merge:
 529  * @diamond: the diamond
 530  * @sphere:  the sphere
 531  *
 532  * "Merge" a diamond back into two parent triangles. The original two triangles
 533  * are added back into the sphere and the four child triangles as well as the
 534  * diamond are removed.
 535  */
 536 void roam_diamond_merge(RoamDiamond *diamond, RoamSphere *sphere)
 537 {
 538         //g_message("roam_diamond_merge: %p, e=%f\n", diamond, diamond->error);
 539
 540         /* TODO: pick the best split */
 541         sphere->polys -= 2;
 542
 543         /* Use nicer temp names */
 544         RoamTriangle *s = diamond->parents[0]; // Self
 545         RoamTriangle *b = diamond->parents[1]; // Base
 546
 547         RoamTriangle *sl = s->kids[0];
 548         RoamTriangle *sr = s->kids[1];
 549         RoamTriangle *bl = b->kids[0];
 550         RoamTriangle *br = b->kids[1];
 551
 552         s->kids[0] = s->kids[1] = NULL;
 553         b->kids[0] = b->kids[1] = NULL;
 554
 555         /* Add original triangles */
 556         roam_triangle_add(s, sl->t.b, b, sr->t.b, sphere);
 557         roam_triangle_add(b, bl->t.b, s, br->t.b, sphere);
 558
 559         roam_triangle_sync_neighbors(s, sl, sl->t.b);
 560         roam_triangle_sync_neighbors(s, sr, sr->t.b);
 561         roam_triangle_sync_neighbors(b, bl, bl->t.b);
 562         roam_triangle_sync_neighbors(b, br, br->t.b);
 563
 564         /* Remove child triangles */
 565         roam_triangle_remove(sl, sphere);
 566         roam_triangle_remove(sr, sphere);
 567         roam_triangle_remove(bl, sphere);
 568         roam_triangle_remove(br, sphere);
 569
 570         /* Add/Remove triangles */
 571         if (s->t.l->t.l == s->t.r->t.r &&
 572             s->t.l->t.l != s && s->parent) {
 573                 roam_diamond_update_errors(s->parent, sphere);
 574                 roam_diamond_add(s->parent, sphere);
 575         }
 576
 577         if (b->t.l->t.l == b->t.r->t.r &&
 578             b->t.l->t.l != b && b->parent) {
 579                 roam_diamond_update_errors(b->parent, sphere);
 580                 roam_diamond_add(b->parent, sphere);
 581         }
 582
 583         /* Remove and free diamond and child triangles */
 584         roam_diamond_remove(diamond, sphere);
 585         g_assert(sl->p.m == sr->p.m &&
 586                  sr->p.m == bl->p.m &&
 587                  bl->p.m == br->p.m);
 588         g_assert(sl->p.m->tris == 0);
 589         roam_triangle_free(sl);
 590         roam_triangle_free(sr);
 591         roam_triangle_free(bl);
 592         roam_triangle_free(br);
 593         g_free(diamond);
 594 }
 595
 596 /**
 597  * roam_diamond_update_errors:
 598  * @diamond: the diamond
 599  * @sphere:  the sphere to use when updating errors
 600  *
 601  * Update the error value associated with a diamond. Called when the view
 602  * changes.
 603  */
 604 void roam_diamond_update_errors(RoamDiamond *diamond, RoamSphere *sphere)
 605 {
 606         roam_triangle_update_errors(diamond->parents[0], sphere);
 607         roam_triangle_update_errors(diamond->parents[1], sphere);
 608         diamond->error = MAX(diamond->parents[0]->error, diamond->parents[1]->error);
 609 }
 610
 611 /**************
 612  * RoamSphere *
 613  **************/
 614 /**
 615  * roam_sphere_new:
 616  *
 617  * Create a new sphere
 618  *
 619  * Returns: the sphere
 620  */
 621 RoamSphere *roam_sphere_new()
 622 {
 623         RoamSphere *sphere = g_new0(RoamSphere, 1);
 624         sphere->polys       = 8;
 625         sphere->triangles   = g_pqueue_new((GCompareDataFunc)tri_cmp, NULL);
 626         sphere->diamonds    = g_pqueue_new((GCompareDataFunc)dia_cmp, NULL);
 627
 628         RoamPoint *vertexes[] = {
 629                 roam_point_new( 90,   0,  0), // 0 (North)
 630                 roam_point_new(-90,   0,  0), // 1 (South)
 631                 roam_point_new(  0,   0,  0), // 2 (Europe/Africa)
 632                 roam_point_new(  0,  90,  0), // 3 (Asia,East)
 633                 roam_point_new(  0, 180,  0), // 4 (Pacific)
 634                 roam_point_new(  0, -90,  0), // 5 (Americas,West)
 635         };
 636         int _triangles[][2][3] = {
 637                 /*lv mv rv   ln, bn, rn */
 638                 {{2,0,3}, {3, 4, 1}}, // 0
 639                 {{3,0,4}, {0, 5, 2}}, // 1
 640                 {{4,0,5}, {1, 6, 3}}, // 2
 641                 {{5,0,2}, {2, 7, 0}}, // 3
 642                 {{3,1,2}, {5, 0, 7}}, // 4
 643                 {{4,1,3}, {6, 1, 4}}, // 5
 644                 {{5,1,4}, {7, 2, 5}}, // 6
 645                 {{2,1,5}, {4, 3, 6}}, // 7
 646         };
 647
 648         for (int i = 0; i < 6; i++)
 649                 roam_point_update_height(vertexes[i]);
 650         for (int i = 0; i < 8; i++)
 651                 sphere->roots[i] = roam_triangle_new(
 652                         vertexes[_triangles[i][0][0]],
 653                         vertexes[_triangles[i][0][1]],
 654                         vertexes[_triangles[i][0][2]],
 655                         NULL);
 656         for (int i = 0; i < 8; i++)
 657                 roam_triangle_add(sphere->roots[i],
 658                         sphere->roots[_triangles[i][1][0]],
 659                         sphere->roots[_triangles[i][1][1]],
 660                         sphere->roots[_triangles[i][1][2]],
 661                         sphere);
 662         for (int i = 0; i < 8; i++)
 663                 g_debug("RoamSphere: new - %p edge=%f,%f,%f,%f", sphere->roots[i],
 664                                 sphere->roots[i]->edge.n,
 665                                 sphere->roots[i]->edge.s,
 666                                 sphere->roots[i]->edge.e,
 667                                 sphere->roots[i]->edge.w);
 668
 669         return sphere;
 670 }
 671
 672 /**
 673  * roam_sphere_update_view
 674  * @sphere: the sphere
 675  *
 676  * Recreate the sphere's view matrices based on the current OpenGL state.
 677  */
 678 void roam_sphere_update_view(RoamSphere *sphere)
 679 {
 680         if (!sphere->view)
 681                 sphere->view = g_new0(RoamView, 1);
 682         glGetDoublev (GL_MODELVIEW_MATRIX,  sphere->view->model);
 683         glGetDoublev (GL_PROJECTION_MATRIX, sphere->view->proj);
 684         glGetIntegerv(GL_VIEWPORT,          sphere->view->view);
 685         sphere->view->version++;
 686 }
 687
 688 /**
 689  * roam_sphere_update_errors
 690  * @sphere: the sphere
 691  *
 692  * Update triangle and diamond errors in the sphere.
 693  */
 694 void roam_sphere_update_errors(RoamSphere *sphere)
 695 {
 696         g_debug("RoamSphere: update_errors - polys=%d", sphere->polys);
 697         GPtrArray *tris = g_pqueue_get_array(sphere->triangles);
 698         GPtrArray *dias = g_pqueue_get_array(sphere->diamonds);
 699
 700         roam_sphere_update_view(sphere);
 701
 702         for (int i = 0; i < tris->len; i++) {
 703                 RoamTriangle *triangle = tris->pdata[i];
 704                 roam_triangle_update_errors(triangle, sphere);
 705                 g_pqueue_priority_changed(sphere->triangles, triangle->handle);
 706         }
 707
 708         for (int i = 0; i < dias->len; i++) {
 709                 RoamDiamond *diamond = dias->pdata[i];
 710                 roam_diamond_update_errors(diamond, sphere);
 711                 g_pqueue_priority_changed(sphere->diamonds, diamond->handle);
 712         }
 713
 714         g_ptr_array_free(tris, TRUE);
 715         g_ptr_array_free(dias, TRUE);
 716 }
 717
 718 /**
 719  * roam_sphere_split_one
 720  * @sphere: the sphere
 721  *
 722  * Split the triangle with the greatest error.
 723  */
 724 void roam_sphere_split_one(RoamSphere *sphere)
 725 {
 726         RoamTriangle *to_split = g_pqueue_peek(sphere->triangles);
 727         if (!to_split) return;
 728         roam_triangle_split(to_split, sphere);
 729 }
 730
 731 /**
 732  * roam_sphere_merge_one
 733  * @sphere: the sphere
 734  *
 735  * Merge the diamond with the lowest error.
 736  */
 737 void roam_sphere_merge_one(RoamSphere *sphere)
 738 {
 739         RoamDiamond *to_merge = g_pqueue_peek(sphere->diamonds);
 740         if (!to_merge) return;
 741         roam_diamond_merge(to_merge, sphere);
 742 }
 743
 744 /**
 745  * roam_sphere_split_merge
 746  * @sphere: the sphere
 747  *
 748  * Perform a predetermined number split-merge iterations.
 749  *
 750  * Returns: the number splits and merges done
 751  */
 752 gint roam_sphere_split_merge(RoamSphere *sphere)
 753 {
 754         gint iters = 0, max_iters = 500;
 755         //gint target = 4000;
 756         gint target = 2000;
 757         //gint target = 500;
 758
 759         if (!sphere->view)
 760                 return 0;
 761
 762         if (target - sphere->polys > 100) {
 763                 //g_debug("RoamSphere: split_merge - Splitting %d - %d > 100", target, sphere->polys);
 764                 while (sphere->polys < target && iters++ < max_iters)
 765                         roam_sphere_split_one(sphere);
 766         }
 767
 768         if (sphere->polys - target > 100) {
 769                 //g_debug("RoamSphere: split_merge - Merging %d - %d > 100", sphere->polys, target);
 770                 while (sphere->polys > target && iters++ < max_iters)
 771                         roam_sphere_merge_one(sphere);
 772         }
 773
 774         while (((RoamTriangle*)g_pqueue_peek(sphere->triangles))->error >
 775                ((RoamDiamond *)g_pqueue_peek(sphere->diamonds ))->error &&
 776                iters++ < max_iters) {
 777                 //g_debug("RoamSphere: split_merge - Fixing 1 %f > %f && %d < %d",
 778                 //              ((RoamTriangle*)g_pqueue_peek(sphere->triangles))->error,
 779                 //              ((RoamDiamond *)g_pqueue_peek(sphere->diamonds ))->error,
 780                 //              iters-1, max_iters);
 781                 roam_sphere_merge_one(sphere);
 782                 roam_sphere_split_one(sphere);
 783         }
 784
 785         return iters;
 786 }
 787
 788 /**
 789  * roam_sphere_draw:
 790  * @sphere: the sphere
 791  *
 792  * Draw the sphere. Use for debugging.
 793  */
 794 void roam_sphere_draw(RoamSphere *sphere)
 795 {
 796         g_debug("RoamSphere: draw");
 797         g_pqueue_foreach(sphere->triangles, (GFunc)roam_triangle_draw, NULL);
 798 }
 799
 800 /**
 801  * roam_sphere_draw_normals
 802  * @sphere: the sphere
 803  *
 804  * Draw all the surface normal vectors for the sphere. Used while debugging.
 805  */
 806 void roam_sphere_draw_normals(RoamSphere *sphere)
 807 {
 808         g_debug("RoamSphere: draw_normal");
 809         g_pqueue_foreach(sphere->triangles, (GFunc)roam_triangle_draw_normal, NULL);
 810 }
 811
 812 static GList *_roam_sphere_get_leaves(RoamTriangle *triangle, GList *list, gboolean all)
 813 {
 814         if (triangle->kids[0] && triangle->kids[1]) {
 815                 if (all) list = g_list_prepend(list, triangle);
 816                 list = _roam_sphere_get_leaves(triangle->kids[0], list, all);
 817                 list = _roam_sphere_get_leaves(triangle->kids[1], list, all);
 818                 return list;
 819         } else {
 820                 return g_list_prepend(list, triangle);
 821         }
 822 }
 823
 824 static GList *_roam_sphere_get_intersect_rec(RoamTriangle *triangle, GList *list,
 825                 gboolean all, gdouble n, gdouble s, gdouble e, gdouble w)
 826 {
 827         gdouble tn = triangle->edge.n;
 828         gdouble ts = triangle->edge.s;
 829         gdouble te = triangle->edge.e;
 830         gdouble tw = triangle->edge.w;
 831
 832         gboolean debug = FALSE  &&
 833                 n==90 && s==45 && e==-90 && w==-180 &&
 834                 ts > 44 && ts < 46;
 835
 836         if (debug)
 837                 g_message("t=%p: %f < %f || %f > %f || %f < %f || %f > %f",
 838                             triangle, tn,   s,   ts,   n,   te,   w,   tw,   e);
 839         if (tn <= s || ts >= n || te <= w || tw >= e) {
 840                 /* No intersect */
 841                 if (debug) g_message("no intersect");
 842                 return list;
 843         } else if (tn <= n && ts >= s && te <= e && tw >= w) {
 844                 /* Triangle is completely contained */
 845                 if (debug) g_message("contained");
 846                 if (all) list = g_list_prepend(list, triangle);
 847                 return _roam_sphere_get_leaves(triangle, list, all);
 848         } else if (triangle->kids[0] && triangle->kids[1]) {
 849                 /* Paritial intersect with children */
 850                 if (debug) g_message("edge w/ child");
 851                 if (all) list = g_list_prepend(list, triangle);
 852                 list = _roam_sphere_get_intersect_rec(triangle->kids[0], list, all, n, s, e, w);
 853                 list = _roam_sphere_get_intersect_rec(triangle->kids[1], list, all, n, s, e, w);
 854                 return list;
 855         } else {
 856                 /* This triangle is an edge case */
 857                 if (debug) g_message("edge");
 858                 return g_list_prepend(list, triangle);
 859         }
 860 }
 861
 862 /**
 863  * roam_sphere_get_intersect
 864  * @sphere: the sphere
 865  * @all: TRUE if non-leaf triangle should be returned as well
 866  * @n: the northern edge
 867  * @s: the southern edge
 868  * @e: the eastern edge
 869  * @w: the western edge
 870  *
 871  * Lookup triangles withing the sphere that intersect a given lat-lon box.
 872  *
 873  * Returns: the list of intersecting triangles.
 874  */
 875 /* Warning: This grabs pointers to triangles which can be changed by other
 876  * calls, e.g. split_merge. If you use this, you need to do some locking to
 877  * prevent the returned list from becomming stale. */
 878 GList *roam_sphere_get_intersect(RoamSphere *sphere, gboolean all,
 879                 gdouble n, gdouble s, gdouble e, gdouble w)
 880 {
 881         /* I think this is correct..
 882          * i_cost = cost for triangle-rectagnle intersect test
 883          * time = n_tiles * 2*tris_per_tile * i_cost
 884          * time = 30      * 2*333           * i_cost = 20000 * i_cost */
 885         GList *list = NULL;
 886         for (int i = 0; i < G_N_ELEMENTS(sphere->roots); i++)
 887                 list = _roam_sphere_get_intersect_rec(sphere->roots[i],
 888                                 list, all, n, s, e, w);
 889         return list;
 890 }
 891
 892 static void roam_sphere_free_tri(RoamTriangle *triangle)
 893 {
 894         if (--triangle->p.l->tris == 0) g_free(triangle->p.l);
 895         if (--triangle->p.m->tris == 0) g_free(triangle->p.m);
 896         if (--triangle->p.r->tris == 0) g_free(triangle->p.r);
 897         roam_triangle_free(triangle);
 898 }
 899
 900 /**
 901  * roam_sphere_free
 902  * @sphere: the sphere
 903  *
 904  * Free data associated with a sphere
 905  */
 906 void roam_sphere_free(RoamSphere *sphere)
 907 {
 908         g_debug("RoamSphere: free");
 909         /* Slow method, but it should work */
 910         while (sphere->polys > 8)
 911                 roam_sphere_merge_one(sphere);
 912         /* TODO: free points */
 913         g_pqueue_foreach(sphere->triangles, (GFunc)roam_sphere_free_tri, NULL);
 914         g_pqueue_free(sphere->triangles);
 915         g_pqueue_free(sphere->diamonds);
 916         g_free(sphere->view);
 917         g_free(sphere);
 918 }